With conventional lighting systems, when numerous light sources are provided in a hall for example, the light intensities of the light sources are adjusted individually to set the illumination appropriately for numerous locations inside the hall. With such a technique, it is necessary to repetitively adjust each of the light sources using trial and error to set the illumination at a predetermined position to a desired value. Also, it is necessary to adjust the light intensity of each of the light sources regularly or for each performance, if the illumination of the lamps changes over time. Similarly, adjustments are necessary when the illuminant has degraded and is replaced. And in conference rooms or the like, the immediate optimal illumination varies when the outside light from a window varies.
On the other hand, systems capable of sensing the condition of each light source, detecting malfunctions, and remotely controlling the respective illuminations of the light sources are known as intelligent lighting systems (for example see Shomei Shisutemu no Chitekika Sekkei (Incorporating Greater Intelligence in the Design of Lighting Systems), Mitsunori Miki and Takafumi Kozai, Doshisha University, Science and Engineering Research Report, July 1998, Volume 39, No. 2, pp 24-34).